Workpieces, including food products, are portioned or otherwise cut into smaller pieces by processors in accordance with customer needs. Also, excess fat, bones, and other foreign or undesired materials are routinely trimmed from food products. It is usually highly desirable to portion and/or trim the food products into uniform sizes, for example, for steaks to be served at restaurants or chicken fillets used in frozen dinners or in chicken burgers.
Much of the portioning/trimming of workpieces, in particular food products, is now carried out with the use of high-speed portioning machines. These machines use various scanning techniques to ascertain the size and shape of the food product as it is being advanced on a moving conveyor. This information is analyzed with the aid of a computer to determine how to most efficiently portion the food product into optimum sizes. For example, a customer may desire chicken breast portions in two different weight sizes, but with no fat or with a limited amount of acceptable fat. The chicken breast is scanned as it moves on an conveyor belt and a determination is made through the use of a computer as to how best to portion the chicken breast to the weights desired by the customer, with no or limited amount of fat, so as to use the chicken breast most effectively.
Portioning and/or trimming of the workpiece can be carried out by various cutting devices, including high-speed liquid jet cutters (liquids may include, for example, water or liquid nitrogen). In many high-speed portioning systems, several high-speed waterjet cutters are positioned along the length of a conveyor to achieve high throughput of the portioned/cut workpieces. Once the portioning/trimming has occurred, the resulting portions are off-loaded from the cutting conveyor and placed on a take-away conveyor for further processing or, perhaps, to be placed in a storage bin.
As noted above, prior to reaching the cutting devices, the workpiece may be scanned at a scanning station to ascertain physical parameters pertaining to size and/or shape of the workpiece. The scanning station may include an optical scanner, an X-ray scanner, or any other suitable scanning system suitable for ascertaining the physical parameters pertaining to size and/or shape of the workpiece.
In an exemplary prior art scanning station shown in FIG. 1, a conveyor carries a workpiece WP beneath a scanning system 10. The scanning system may be of a variety of different types, including video cameras 12 to view the workpiece WP illuminated by one or more light sources. Light from a light source 14 is extended transversely across a moving conveyor belt 18 of a conveying system 22 to define a sharp shadow or light stripe line 26, as shown in FIG. 2, with the area forwardly of the transverse beam being dark. When no workpiece WP is being carried by the conveyor belt 18, the shadow line/light stripe 26 extends across the belt, only being distorted by the belt. However, when the workpiece WP passes across the shadow line/light stripe, the upper, irregular surface of the workpiece produces an irregular shadow line/light stripe as viewed by video cameras 12 angled downwardly on the workpiece and the shadow line/light stripe. The video cameras 12 detect the displacement of the shadow line/light stripe 26 (i.e., in the z-axis direction) from the position it would occupy if no workpiece were present on the conveyor belt 18 (i.e., from an initial z-axis location), and send appropriate output signals to one or more computers, computing devices, etc., having at least one processor (not shown). This displacement represents the thickness of the workpiece along the shadow line/light stripe. The length of the workpiece is determined by the distance of the belt travel that shadow line/light stripes are created by the workpiece. In this regard, an encoder (not shown) integrated into the conveying system 22 may generate pulses at fixed distance intervals corresponding to the forward movement of the conveyor belt 18 and/or any other belt of the system 22 and send output signals to the computer.
In order for accurate scanning (and therefore accurate portioning or trimming) to occur, it is necessary that the scanning system be very precise and calibrated appropriately. As noted above, in the scanning step, the laser line is visible to the camera in a way that any distortion to the line can be detected by the camera and interpreted by the software as product mass passing the laser line. The more level, flat, and undistorted the laser line can be, the more accurate the scan will be. In this regard, portioners have traditionally used a fabric belt beneath the scanning station that provides a flat surface most suitable for scanning. However, such fabric belts are not suitable for conveying the food product during the cutting/excising process using a waterjet cutter. Rather, for waterjet cutting, a robust metallic belt of a grid or “open” construction is needed to withstand the impact of the high-pressure waterjet as well as allow the waterjet to pass downwardly through the belt, for example, after cutting through the workpiece. As such, the workpiece can be transferred from the initial fabric belt associated with the scanner to a metallic grid-type belt for cutting.
During this transfer process, the workpiece may shift relative to the belt, as well as distort or change shape, due to various causes such as a difference in the speed of the belts, misalignment of the belts, difference in “grip” of the belts on the workpieces, etc. As a consequence, the location of the workpiece on the conveyor, and/or the configuration of the workpiece detected by the scanner, may not coincide with the workpiece that reaches the waterjet or other cutter being used. This can result in inaccuracies in the cutting and/or portioning of the workpiece.
Portioners may instead scan and cut on the same belt, eliminating the transfer point and the problems they can cause. The cutting step is unchanged, but there can be significant differences in scanning. As noted above, a belt used for cutting with a waterjet cutter must be an open metal belt to allow water to flow through. As such, the laser line falls on, and through, the open metal belt, complicating the calibration and scanning process.
Some solutions for calibrating the scanning station include using the transverse cross pins in the belts (see pins 194 in the belt 116 shown in FIG. 5) as a height reference line(s), and/or using software to continuously establish a reference height(s). For instance, referring to FIG. 2b, at block 28, a belt is scanned to identify a pin or a plurality of pins over a period of time. In one embodiment, the belt may be scanned for a first pin(s) by extending light from a light source across the moving conveyor belt to define a sharp shadow or light stripe line/laser, as described above. A video camera or the like may detect a first type of light stripe distortion caused by a first pin(s). If a first type of light stripe distortion from a first pin(s) is detected at decision block 30, appropriate output signal(s) are sent from the video camera to one or more computing devices, computers, etc., having at least one processor, as indicated by block 32. At block 34, the output signals are processed by non-transitory computer-readable medium (such as software) having computer-executable instructions stored thereon that, in response to execution by at least one processor of the one or more computing devices, cause the at least one computing device to perform actions that include determining a first height or z-axis location(s) of the identified first pin(s) along the length of the first pin(s) (i.e., a first height reference line), for instance, relative to a certain reference point along the z-axis. The “height” of the first pin(s) may vary along the length of the pin(s) if the pin(s) is not perfectly linear or straight, accordingly, the pin(s) may have a height or heights (hereinafter sometimes referred to as “pin(s) height(s)”).
When a first pin(s) is located and its height(s) determined, the computing device performs the action of applying a predetermined offset to the determined first pin height(s) to define the second height(s) or z-axis location(s) of the top of the belt and the bottom of the product, as indicated by block 38. The belt may then be scanned again, as indicated by block 40, to detect either the first type of light stripe distortion from a second pin(s) or a second type of light stripe distortion from a product on the belt. As indicated by decision block 42, if neither the first nor second light stripe distortion is detected, the belt continues to be scanned at block 40. If a second type of light stripe distortion from a product is detected (i.e., when the laser line passes over the product to show the top of the product), appropriate output signal(s) are sent from the video camera to the one or more computing devices, as indicated by block 44. The computing device performs the action of determining one or more third z-axis location(s) representative of the top surface of the product, as indicated by block 46, and it uses the height difference between the bottom of the product and the top of the product as the product passes the laser line on the moving conveyor belt to perform the action of calculating the volume of the product, as indicated by block 48.
If a first type of light stripe distortion from a second pin(s) is detected at decision block 42, appropriate output signal(s) are sent from the video camera to the one or more computing devices, as indicated by block 50. The computing device processes the output signals to determine a fourth height(s) or z-axis location(s) of the identified second pin(s) along the length of the pin(s), as indicated by block 54. At block 58, the computing device performs the action of applying an offset (based on the different in height between the first and second pins) to the initial or first z-axis location(s) or height(s) of the first scanned pin(s) that was determined at block 34 to recalculate the second height(s) or z-axis location(s) of the top of the belt and the bottom of the product, as indicated by block 38.
It should be noted that the portioning apparatus may also be calibrated, such as in the manner described in U.S. Provisional Patent Application No. 62/431,374, entitled “Methods for Calibrating Portioning Apparatus”, the disclosure of which is incorporated by reference herein.
The offset added to the first pin(s) height(s) (or z-axis location(s)) during the scanning station calibration process does not account for irregularities in the top surface of the belt. For instance, with the belt also being used for cutting, the top surface of the belt will become quite worn over time from the waterjets. Wearing of the belt can distort the laser line at the top surface of the belt. Establishing the pin(s) in the belt as the reference height, and then adding an additional offset helps overcome some of the variability due to wear on the top of the belt. The pins within the belt are fairly stiff, however, without proper support, the pins can sag and bend over time. As the pins continue to sag and bend over time, more offset is needed during calibration, complicating the calibration process and compromising scanning accuracy.
A belt support positioned beneath the scanning portion of the conveyor belt may be used to help prevent the pins from sagging and bending over time. An ideal belt support must provide a completely level surface for the belt to ride over prior to, and after traveling past the laser line. At the same time, the belt support should provide support in a manner that does not interfere with the travel of the belt while being sufficiently durable to withstand the wear of the passing belt. Moreover, the belt support should be configured such that it is not overly reflective so as to interfere with the scanning system and it should be easy to clean.
To meet at least some of these requirements, some prior art systems use substantially non-reflective flat plastic plates beneath the open metal belt in the scanning area. However, the plastic plates often distort over time, even with reinforcements built in, thereby affecting scanning accuracy. Moreover, the plastic plates are difficult to adjust and level to accommodate distortion of the plate and/or wear of the metal belt. Furthermore, the plastic plates are difficult to clean, making hygiene an issue.
Accordingly, an improved belt support configured to support a belt on which a workpiece may be both scanned and portioned is desired.